A moving message display method and apparatus is described in U.S. patent application Ser. No. 436,421 filed Nov. 14, 1989 and U.S. patent application Ser. No. 419,094 filed Oct. 10, 1989, both of which are commonly owned by the assignee of the present application. The teachings of both of these applications are incorporated herein by reference.
U.S. Pat. No. 4,746,981, also assigned to the same assignee, discloses the use of a plurality of stacked television receivers or monitors to display a larger composite image. It is directed to overcoming a problem which arises from improper spatial presentation of lines due to interlace. U.S. patent application Ser. No. 419,094 provides a technique which minimizes the unpleasant effect arising from blanking lines.
From the teaching of U.S. Ser. No. 436,421, moving message display systems are limited by a fixed number of monitors, as exemplified by forming a composite image across a fixed number of stacked monitors. That is, the controlling software which transfers an image from one monitor to the next must be customized for some upper limit of monitors. Adding additional monitors to the message display system beyond this upper limit is troublesome, insofar as the software needs modification to accommodate the larger number of monitors.
In addition, the image is expanded and then split up across all the fixed monitors. Any variation in the number of monitors must be accommodated by the software and, further, the resolution of the image displayed is not as good as it would be if the image were not expanded but rather displayed for the size of a single monitor.
Further, changing the stacking relationship of the monitors would require revising the software to expand the image to conform to the revised stacking relationship. For instance, if four monitors are side by side and their stacking is changed to form a square, the expanded image will need to be changed as well by software. In addition, expanding the image to a larger size means that the central graphics computer must be that much faster to keep track of and process the expanded images. Unfortunately, there is a further limit to the amount of data that can be handled by a computer at its fastest processing speed. This limits the number of monitors which may be utilized in an array.
It would therefore be desireable to provide a video moving message system which may accommodate any number of monitors without requiring modification of software, such modification being otherwise required to change the upper limit of the number of monitors capable of being handled by the software. It would further be desirable to improve the resolution of the image displayed on all monitors to that which would arise if the image were displayed by a single monitor.